A. field of the Invention
The present invention relates to a new and improved cartridge filter and more particularly, to a new and improved cartridge filter including annular concentrically mounted filter elements secured between an impervious end cap and an end cap that includes an outlet and is reinforced by a reinforcing disc.
B. Description of the Prior Art
It is desirable in many fluid systems to recycle the working fluid through a filter to prevent the accumulation of foreign matter that could result in damage or impairment of the system. Concentric filter elements in a filter cartridge housing have been found to be efffective in performing the filtering function. Examples of filter units employing concentric filter elements are disclosed in U.S. Pat. Nos. 3,211,292, 3,988,244 and 4,317,727. The filter devices disclosed in these patents each includes a pair of concentrically mounted filter elements enclosed within a casing or housing between upper and lower end caps. These filter devices employ rigid elements or a filter core such as a plastic netting or a tubular plastic core, positioned between the concentrically mounted filter elements. The rigid elements or filter core prevents collapse of the filter elements due to forces resulting from a pressure drop across the filter elements and maintains the concentric filter elements in proper configuration while defining a passage for flow to the outlet of the filter. The rigid support elements such as disclosed in U.S. Pat. No. 3,211,292 must be of sufficient strength to resist the total force applied to one filter element. The use of these support elements results in complex assembly and manufacturing increasing the cost of the filter. The filter core elements such as disclosed in U.S. Pat. Nos. 3,988,244 and 4,317,727 overcome the disadvantages of using rigid support elements; however, it has been discovered that there is a vertical downward force tending to push the filter core through the outlet in the lower end cap, and damage the filter media. It is desireable to employ the filter core due to the reduced assembly and manufacturing costs while preventing damage to the end cap and the effectiveness of the filter media due to the vertical downward force applied by the filter core.